In the case of an incoming call on analog lines, no defined event exists for signaling the end of a call establishment phase. Such limitation may create various problems as explained below.
For instance, as shown in FIG. 1, there is shown a diagram which discloses how a conflict may occur due to the limitation.
In the case where a first incoming call is provided by an outbound switch to an Application Programming Interface (API) of an inbound terminal, a ring signal for the first incoming call is issued to an application at the inbound terminal. The skilled addressee will appreciate that the incoming call is provided using a ringing voltage on the line. The application may be any type of application such as for instance a voicemail managing application, an authentication application based on incoming call data, Unified Messaging Applications, Automatic Call Distribution (ACD) Server, Voice over IP (VoIP) Gateway, Point of Sales Server (POS), etc. In response to the ring for the first call, the application issues a “Call Accept Command” (i.e., an AT Answer (ATA) command if a port driver or a TTY driver is used as Application Programming Interface (API)) for instance.
If while the “Call Accept Command” is being issued to the API, the party issuing the first incoming call hangs up and therefore causes the first incoming call to be terminated and if a second incoming call issued by another party is being provided to the application, the “Call Accept Command” issued to the API will be applied against the second incoming call causing a conflict.
Such conflict may be the source of Denial of Service (DoS) attacks in the case for instance where an access to an application is based upon a calling or called identity. Incoming calls may also be directed to wrong directions by an application. In the case where the application is an answering machine, a user issuing a call may leave a message in a wrong voicemail.
There is a need for a method and apparatus that will overcome at least one of the above-identified drawbacks.